Many devices requires several switches for operation. For example, one type of portable telephone allows the user to store a series of telephone numbers and allows the user to call a selected telephone number without having to dial that number. For this purpose, the telephone has a display screen that lists the stored numbers, with each party""s name beside a number. A user operates a first or second switch to scroll the list up or down. Once the user has selected the party to call, the user then operates a third switch to automatically call the displayed telephone number. The requirement to provide three separate switches increases the area occupied by the device and the complexity for mounting the switches, and introduces inconvenience because the user has to move his hand between three separate switches. A single actuation member of simple design and very small size, which enabled a user to perform all three functions, would be of value.
In accordance with one embodiment of the present invention, an electric switch assembly is provided which enables the performance of a plurality of switching functions in a switch assembly of small size and simple design. The switch assembly includes a housing with bores extending along a vertical axis, and an actuation member which is moveable vertically along the axis. A dome-shaped switching element is located in the housing and has a center that can be depressed by the actuation member to close a switch. The actuation member has a lower portion that extends through a hole in the center of the dome switching element and that is slidably guided at the bottom of the housing which lies below the switching element. The actuation member can be turned in opposite directions, and is fixed to a coding wheel. In a neutral rotational position, the coding wheel does not close any contacts. However, when the coding wheel is turned to the left or right, contacting parts of the coding wheel engage one or another pair of contacts to close a second or third switch.
The novel features of the invention are set forth with particularity in the appended claims. The invention will be best understood from the following description when read in conjunction with the accompanying drawings.